Regular expression (nonfiction): Difference between revisions
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A '''regular expression''', '''regex''' or '''regexp''' (sometimes called a rational expression) is a sequence of characters that define a search pattern. Usually this pattern is used by string searching algorithms for "find" or "find and replace" operations on strings, or for input validation. It is a technique developed in theoretical computer science and formal language theory. | A '''regular expression''', '''regex''' or '''regexp''' (sometimes called a rational expression) is a sequence of characters that define a search pattern. Usually this pattern is used by string searching algorithms for "find" or "find and replace" operations on strings, or for input validation. It is a technique developed in theoretical computer science and formal language theory. | ||
The concept arose in the 1950s when the American mathematician Stephen Cole Kleene formalized the description of a regular language. The concept came into common use with Unix text-processing utilities. Since the 1980s, different syntaxes for writing regular expressions exist, one being the POSIX standard and another, widely used, being the Perl syntax. | The concept arose in the 1950s when the American mathematician [[Stephen Cole Kleene (nonfiction)|Stephen Cole Kleene]] formalized the description of a regular language. The concept came into common use with Unix text-processing utilities. Since the 1980s, different syntaxes for writing regular expressions exist, one being the POSIX standard and another, widely used, being the Perl syntax. | ||
Regular expressions are used in search engines, search and replace dialogs of word processors and text editors, in text processing utilities such as sed and AWK and in lexical analysis. Many programming languages provide regex capabilities, built-in or via libraries. | Regular expressions are used in search engines, search and replace dialogs of word processors and text editors, in text processing utilities such as sed and AWK and in lexical analysis. | ||
Many programming languages provide regex capabilities, built-in or via libraries. | |||
== Examples == | == Examples == | ||
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== Nonfiction cross-reference == | == Nonfiction cross-reference == | ||
* [[Stephen Cole Kleene (nonfiction)]] - inventor of regular expressions | |||
External links: | External links: | ||
Revision as of 08:25, 23 June 2019
A regular expression, regex or regexp (sometimes called a rational expression) is a sequence of characters that define a search pattern. Usually this pattern is used by string searching algorithms for "find" or "find and replace" operations on strings, or for input validation. It is a technique developed in theoretical computer science and formal language theory.
The concept arose in the 1950s when the American mathematician Stephen Cole Kleene formalized the description of a regular language. The concept came into common use with Unix text-processing utilities. Since the 1980s, different syntaxes for writing regular expressions exist, one being the POSIX standard and another, widely used, being the Perl syntax.
Regular expressions are used in search engines, search and replace dialogs of word processors and text editors, in text processing utilities such as sed and AWK and in lexical analysis.
Many programming languages provide regex capabilities, built-in or via libraries.
Examples
Remove pairs of square brackets and their contents:
\[[^\[]*\]
Source: Stack Overflow
In the News
Fiction cross-reference
Nonfiction cross-reference
- Stephen Cole Kleene (nonfiction) - inventor of regular expressions
External links:
- Regular expression @ Wikipedia